Proper Method to Install Freeze Plug heater?

I recently moved from Arizona to Vermont, where I now live temps of -30 or lower are not uncommon. I have ordered the freeze plug block heater (just to be on the safe side) and after some searching on the forums the installation seems fairly simple but I was wondering how to bleed the air out of the cooling system.

Specifically:

If I remove the plug and let the coolant from the block drain out how do I purge the air from the coolant system?

Would an oil pan magnetic heater also be needed? The car will be garaged for most of the winter, but it is a prized possession so I'd rather be overly cautious.